luk3333 Posted January 24, 2014 Report Share Posted January 24, 2014 My 5k with 20thou over shallow dish pistons and shaved 4k head. DCR of 8.22 SCR of 10.5 280/286 cam inlet closing 66 ABDC standard rods Looking on the hot rod forum in america they say a DCR of 7.75-8.5 is suitable for pump gas. It seems like only the hot rod guys are really interested in DCR for what ever reason. There is a DCR calculator here. What DCR's are everyone else running in their modified K engines? Quote Link to comment Share on other sites More sharing options...
kickn5k Posted January 24, 2014 Report Share Posted January 24, 2014 My 5k with 20thou over shallow dish pistons and shaved 4k head. DCR of 8.22 SCR of 10.5 280/286 cam inlet closing 66 ABDC standard rods Looking on the hot rod forum in america they say a DCR of 7.75-8.5 is suitable for pump gas. It seems like only the hot rod guys are really interested in DCR for what ever reason. There is a DCR calculator here. What DCR's are everyone else running in their modified K engines? Never bothered with DCR's, always gone off static comp. That is a reasonable sized camshaft, I wouldn't be scared to run 11-11.2:1 with that cam and 98 fuel. I personally wouldn't be to stressed at what the yanks do. Highest pump octane they run is 93. But then again I'm pretty sure they rate octane differently. Quote Link to comment Share on other sites More sharing options...
luk3333 Posted January 31, 2014 Author Report Share Posted January 31, 2014 Yea, they use MON and we use RON or something? Pretty sure its means is rated under different test conditions. Punching 11.2CR and the other stats for my engine in and it gives a DCR of 8.72 which isn't that far above their apparent limit of 8.5 and if our 98 is of higher octane than their best pump fuel it would probably be ok. Quote Link to comment Share on other sites More sharing options...
luk3333 Posted January 31, 2014 Author Report Share Posted January 31, 2014 Also I was just playing around with the boost setting on the calculator, if you put 6psi with 9.5CR and inlet closing at 20ATDC you get a DCR of 13, but people use those sort of setting and don't get detonation. Is it harder to detonate an air fuel mixture under pressure? Quote Link to comment Share on other sites More sharing options...
philbey Posted February 9, 2014 Report Share Posted February 9, 2014 My static comp is 11.5 or perhaps more, can't remember my dynamic but I did look at it, with a very big cam it runs great on 98 Ron Quote Link to comment Share on other sites More sharing options...
luk3333 Posted February 11, 2014 Author Report Share Posted February 11, 2014 Can you remember your cam specs? I'd be interested to pop the details into the calculator if you don't mind :) Quote Link to comment Share on other sites More sharing options...
filfrederick Posted February 11, 2014 Report Share Posted February 11, 2014 i ran 11.1-1 with 294deg cams and 105deg timing it ran fine with no detonation at all on 98 it was quite hard to start tho, had to use a landcruiser v8 reduction starter motor. Quote Link to comment Share on other sites More sharing options...
filfrederick Posted February 11, 2014 Report Share Posted February 11, 2014 and 8mm lift Quote Link to comment Share on other sites More sharing options...
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